Process for fabricating RuSixOy-containing adhesion layers

ABSTRACT

A method for use in the fabrication of integrated circuits includes providing a substrate assembly having a surface. An adhesion layer is formed over at least a portion of the surface. The adhesion layer is formed of RuSi x O y , where x and y are in the range of about 0.01 to about 10. The adhesion layer may be formed by depositing RuSi x O y  by chemical vapor deposition, atomic layer deposition, or physical vapor deposition or the adhesion layer may be formed by forming a layer of ruthenium or ruthenium oxide over a silicon-containing region and performing an anneal to form RuSi x O y  from the layer of ruthenium and silicon from the adjacent silicon-containing region. Capacitor electrodes, interconnects or other structures may be formed with such an adhesion layer. Semiconductor structures and devices can be formed to include adhesion layers formed of RuSi x O y .

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor devices and thefabrication thereof. More particularly, the present invention pertainsto RuSi_(x)O_(y)-containing adhesion layers, structures incorporatingsuch adhesion layers, and methods of fabricating the same.

2. State of the Art

Integrated circuits typically include various conductive layers. Forexample, in the fabrication of semiconductor devices, such as dynamicrandom access memories (DRAMs) and static random access memories(SRAMs), conductive materials (e.g., electrode materials such as Pt andRu) are typically expected to be used in the formation of storage cellcapacitors and interconnection structures (e.g., conductive layers incontact holes, vias, etc.). In integrated circuits, conductive materialsmay require some sort of adhesion layer in order to prevent delaminationof the films. In forming such integrated circuit structures, theadhesion layer must be able to withstand the various anneals performedon the capacitor electrode and dielectric. The adhesion of grown anddeposited films used in semiconductor processing must be excellent bothas deposited and after subsequent processing. If films lift from thesubstrate device, failure can result, leading to potential reliabilityproblems. For example, failure of the adhesive can result in fracture ofthe mechanical bond (e.g., die separation) or failure of the circuit bydegradation (e.g., contamination or loss of thermal or electricalproperties) and could preclude the use of the desired film.

Use of various adhesive layers is known in the art. For example, insilicon devices having small diameter contact holes and tungsten fillingthe contact holes, tungsten is typically used as a contact fillmaterial, which requires the use of an underlying contact layer as wellas an underlying adhesion layer. The contact layer is needed to provideboth good ohmic contact to the silicon device, and also serves as anadhesion layer between the tungsten fill and the sides of a siliconoxide contact hole. Titanium is usually used for this purpose, providinggood ohmic contact, after centering converts titanium to titaniumdisilicide at the bottom of the contact hole. However, where only atitanium adhesive layer is used, the subsequent tungsten chemical vapordeposition process severely damages the exposed titanium. The tungstendeposition is performed via the decomposition of tungsten hexafluoride,and in addition to the deposition of tungsten, a serious reaction withtitanium occurs, eroding the critical contact and adhesive layer. Toovercome the titanium erosion phenomena, an adhesion layer of eithersputtered tungsten or titanium nitride on the titanium layer has beensuggested. For example, U.S. Pat. No. 5,286,675 describes a process inwhich a titanium-titanium nitride composite is used in contact holesprior to filling with tungsten. However, that process does notsufficiently eliminate the attack of titanium, particularly where poortitanium nitride coverage exists. The lack of adequate titanium nitridecoverage leads to erosion of the underlying titanium adhesive layerduring the subsequent tungsten deposition process, resulting in a lackof tungsten adhesion, which is described as “tungsten peeling” or the“volcano effect.”

Adhesion layers have also been employed for providing adhesion between asubstrate and overlying seed layers in metallization areas ofsubstrates. For example, U.S. Pat. No. 5,126,016 provides a chromiumadhesion layer for thin-film microelectronic circuitry. However, themetallization of high aspect ratio thin-film structures cause highstress which may lead to adhesions failure, as described above.

Various metals and metallic compounds (e.g., metals such as platinum andconductive metal oxides such as ruthenium oxide) have been proposed foruse as electrodes or as electrode stack layers with high dielectricconstant materials. However, such electrical connections must beconstructed so as to not diminish the beneficial properties of thehigh-dielectric constant materials. For example, in order for platinumor ruthenium oxide to function well as a bottom electrode or as one ofthe layers of an electrode stack, an oxidation-resistant barrier layerand adhesive layer are typically required. These layers, either as acombined layer or as individual layers, must provide adhesion between asubstrate and deposited layers and prevent oxidation of silicon locatedat the surface of the electrode stack during the oxygen anneal of thehigh dielectric constant materials (e.g., Ta₂O₅ or BaSrTiO₃), whichoxidation can result in a decreased series capacitance and, in turn,degradation of the storage capacity of the cell capacitor. Similarly, O₂diffusing through the platinum or RuO₂ to the underlying Si yields SiO₂at the base of the electrode, thus decreasing series capacitance.Platinum and ruthenium oxide, when used alone as an electrode andadhered to, are generally too permeable to oxygen and silicon to be usedas a bottom electrode of a storage cell capacitor formed on a siliconsubstrate region.

In view of the aforementioned shortcomings of the methods and structuresbeing currently practiced, it would be advantageous to provide anadhesion layer that prevents delamination of deposited films contactingthe same, withstands the various anneals performed on the capacitorelectrode and dielectric, maintains the performance of high dielectriccapacitors, prevents oxidation of underlying Si contacts, and preventsSi diffusion into an electrode or dielectric. It would be of furtheradvantage to form an adhesion layer that can survive a tape test both asdeposited and after an annealing step and that reduces or eliminates thediffusion or migration of ruthenium into an elemental Si or a silicidelayer, or vice versa, which typically occurs as a result of the highsolubility of silicon in ruthenium.

SUMMARY OF THE INVENTION

The present invention provides RuSi_(x)O_(y)-containing adhesion layers,along with structures incorporating such adhesion layers and methods offabricating the same.

A method of fabricating semiconductor devices and assemblies (e.g.,integrated circuits) according to the present invention includesproviding a substrate assembly having a surface. An adhesion layer isformed over at least a portion of the surface. The adhesion layerincludes RuSi_(x)O_(y), where x and y are in the range of about 0.01 toabout 10. The adhesion layer may, additionally, include Ru and/orRuSi_(x). In one particular embodiment of the method, the adhesion layeris formed of RuSi_(x)O_(y), where x is in the range of about 0.1 toabout 3, and more preferably is about 0.4, and where y is in the rangeof about 0.01 to about 0.1, and more preferably is about 0.05.

In another embodiment of the method, the adhesion layer is formed bydepositing a mixed film of Ru—RuSi_(x)—RuSi_(x)O_(y) by chemical vapordeposition (CVD). In yet another embodiment of the method, the adhesionlayer is formed by CVD deposition of Ru—RuSi_(x)O_(y) in an oxidizingatmosphere, such as O₂, N₂O, O₃, or any other suitable inorganic ororganic oxidizer. All of the foregoing adhesion layers may also beformed by atomic layer deposition. This process can result in theformation of multiple (preferably up to 300) RuSi_(x)O_(y)-containingdiffusion adhesion monolayers and, more preferably, formation of fromthree to five monolayers of RuSi_(x)O_(y)-containing adhesion layers.

In an alternative embodiment, the adhesion layer is formed by physicalvapor deposition (PVD) of the adhesion layers of the present invention.In one particular embodiment of the PVD deposition method, mixed filmsof Ru—RuSi_(x)—RuSi_(x)O_(y) are deposited to form an adhesion layer.Alternatively, mixed films of Ru—RuSi_(x)O_(y) may be deposited to forman adhesion layer.

According to yet another method of the present invention, a capacitor isformed by providing a silicon-containing region of a substrate assembly.A first electrode is then formed on at least a portion of thesilicon-containing region of the substrate assembly. The first electrodeincludes an adhesion layer having RuSi_(x)O_(y), where x and y are inthe range of about 0.01 to about 10. A high dielectric material is thenformed over at least a portion of the first electrode and a secondelectrode is provided over the high dielectric material. The secondelectrode may also include an adhesion layer having RuSi_(x)O_(y), wherex and y are in the range of about 0.01 to about 10.

In an alternative embodiment of the method, one or more conductivelayers are formed relative to the RuSi_(x)O_(y)-containing adhesionlayer. The one or more conductive layers are formed of at least one of ametal or a conductive metal oxide, e.g., formed from materials selectedfrom the group of RuO₂, RhO₂, MoO₂, IrO₂, Sr RuO₃, Ru, Rh, Pd, Pt, andIr.

A semiconductor device structure according to the present inventionincludes a substrate assembly including a surface and an adhesion layerover at least a portion of the surface. The adhesion layer is formed ofRuSi_(x)O_(y), where x and y are in the range of about 0.01 to about 10.

In one embodiment of the structure, at least a portion of the surface isa silicon-containing surface and the structure includes one or moreadditional conductive layers over the adhesion layer formed of at leastone of a metal and a conductive metal oxide, e.g., formed from materialsselected from the group of RuO₂, RhO₂, MoO₂, IrO₂, Ru, Rh, Pd, Pt, andIr.

Semiconductor assemblies and structures according to the presentinvention are also described. One embodiment of such a structureincludes a capacitor structure having a first electrode, a highdielectric material on at least a portion of the first electrode, and asecond electrode on the dielectric material. At least one of the firstand second electrodes includes an adhesion layer formed ofRuSi_(x)O_(y), where x and y are in the range of about 0.01 to about 10.

Another such structure is an integrated circuit including a substrateassembly including at least one active device and a silicon-containingregion. An interconnect is formed relative to the at least one activedevice and the silicon-containing region. The interconnect includes anadhesion layer on at least a portion of the silicon-containing region.The adhesion layer is formed of RuSi_(x)O_(y), where x and y are in therange of about 0.01 to about 10.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading thefollowing detailed description taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 shows a device structure including a RuSi_(x)O_(y)-containingadhesion layer according to the present invention;

FIGS. 2-4 show one method of forming the RuSi_(x)O_(y)-containingadhesion layer according to the present invention;

FIG. 5 shows a structure including a RuSi_(x)O_(y)-containing adhesionlayer according to the present invention as part of a multipleconductive layer stack;

FIG. 6 is a structure showing a high dielectric capacitor including anelectrode having a RuSi_(x)O_(y)-containing adhesion layer according tothe present invention;

FIG. 7 illustrates the use of a RuSi_(x)O_(y)-containing adhesion layerin a storage cell capacitor application; and

FIG. 8 illustrates the use of a RuSi_(x)O_(y)-containing adhesion layerin a contact application.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a structure 20 according to the present inventionincludes a substrate assembly 21 and a RuSi_(x)O_(y)-containing adhesionlayer 23 disposed on a surface 22 of the substrate assembly 21, e.g., asilicon-containing substrate. The structure 20 further includes aconductive layer 24. As used herein, “substrate assembly” refers toeither a semiconductor substrate such as the base semiconductor layer(e.g., base silicon layer of a wafer), a silicon layer deposited onanother material (e.g., silicon on sapphire), or a semiconductorsubstrate having one or more layers, structures, and/or regions formedthereon or therein. It is understood that reference to a substrateassembly herein also includes any known process steps that may have beenpreviously used to form or define regions, junctions, various structuresor features, and openings (e.g., vias, contact openings, high aspectratio openings, etc.).

The structure 20 is representative of a RuSi_(x)O_(y)-containingadhesion layer that may be used for any application requiring aneffective adhesion layer, for example, to adhere two adjacent layerstogether, prevent delamination of films in a semiconductor structure,and to prevent oxidation of an underlying Si contact. TheRuSi_(x)O_(y)-containing adhesion layer 23 may be used in thefabrication of semiconductor devices or assemblies where it is necessaryor desirable to enhance or ensure adhesion of one material to anadjacent material. As described more fully hereinafter, theRuSi_(x)O_(y)-containing adhesion layer 23 may include Ru and/orRuSi_(x), in addition to RuSi_(x)O_(y).

The substrate assembly 21 may, for example, be representative of acontact structure having an opening extending to a silicon-containingsurface. In such a structure, adhesion layers are commonly used withinthe contact opening to prevent undesirable reactions, such as reactionsbetween the conductive contact material and the silicon-containingsurface that lead to erosion of one or both such layers and a generallack of adhesion between the contact and silicon-containing materials.By way of example, the RuSi_(x)O_(y)-containing adhesion layer 23 may beinterposed between other layers of materials (e.g., ruthenium oxide,platinum, etc.) forming an electrode of a capacitor.

It is understood that persons having ordinary skill in the art willrecognize that the adhesion layers of the present invention can be usedin any semiconductor processes, structures, assemblies and devices(e.g., CMOS devices and memory devices) which utilize adhesion layers.

The amount of elemental Si and SiO₂ incorporated into theRuSi_(x)O_(y)-containing adhesion layer 23 is sufficient to accomplishadhesion and oxidation resistance in between one or more layers ofmaterials in semiconductor devices. Preferably, theRuSi_(x)O_(y)-containing adhesion layer 23 includes an atomiccomposition such that x and y are in the range of about 0.01 to about10. More preferably, x and y are in the range of about 1 to about 3, andyet more preferably, x is about 0.4 and y is about 0.05. Likewise, inembodiments of the invention where the RuSi_(x)O_(y)-containing adhesionlayer 23 of the present invention contains RuSi_(x), the RuSi_(x)includes an atomic composition such that x is in the range of about 0.01to about 10, and more preferably in the range of about 0.1 to about 0.5,and yet more preferably, x is about 0.4.

The thickness of the RuSi_(x)O_(y)-containing adhesion layer 23 isdependent upon the application for which it is used. Preferably, thethickness is in the range of about 10 Å to 1,000 Å. More preferably, thethickness of the RuSi_(x)O_(y)-containing adhesion layer 23 is in therange of about 50 Å to about 500 Å. For example, this preferredthickness range of about 50 Å to about 500 Å is applicable to aRuSi_(x)O_(y)-containing adhesion layer used for forming a bottomelectrode stack of a capacitor structure.

The conductive layer 24 shown in FIG. 1 is representative of one or morelayers. For example, the conductive layer 24 may include one or morelayers formed of a metal or metal oxide, or combinations thereof Suchlayers may include one of RuO₂, MoO₂, Rh, RhO₂, IrO₂, Ru, Pt, Pd and Ir,such as when the RuSi_(x)O_(y)-containing adhesion layer is used in anelectrode stack. Alternatively, the conductive layer 24 may be a contactmaterial, such as aluminum, when the RuSi_(x)O_(y)-containing adhesionlayer is used in a contact or interconnect application. Such conductivelayers may be formed by any method known to those skilled in the art.

The RuSi_(x)O_(y)-containing adhesion layer 23 may be formed by variousprocesses. For example, the formation of the RuSi_(x)O_(y)-containingadhesion layer may be sputter deposited from a deposition target ofRuSi_(x)O_(y), may be deposited by the sputtering from a depositiontarget of ruthenium onto a silicon-containing surface followed by ananneal, may be deposited by physical vapor deposition (PVD) ofRu—RuSi_(x)—RuSi_(x)O_(y) mixed films, may be deposited by CVD using aruthenium precursor and a silicon precursor in an oxidizing atmosphere,or may be deposited by CVD of Ru—RuSi_(x)—RuSi_(x)O_(y) films. SuitableCVD processes include, for example, atmospheric pressure chemical vapordeposition (APCVD), low pressure chemical vapor deposition (LPCVD),plasma enhanced chemical vapor deposition (PECVD), or any other knownchemical vapor deposition technique. Further, theRuSi_(x)O_(y)-containing adhesion layer may be formed by depositing alayer of ruthenium using CVD onto a silicon-containing surface followedby an annealing process.

The aforementioned CVD processes may be carried out in a chemical vapordeposition reactor, such as a reaction chamber available under the tradedesignation of 7000 from Genus, Inc. (Sunnyvale, Calif.), a reactionchamber available under the trade designation of 5000 from AppliedMaterials, Inc. (Santa Clara, Calif.), or a reaction chamber availableunder the trade designation of Prism from Novelus, Inc. (San Jose,Calif.). However, any reaction chamber suitable for performing CVD maybe used.

Oxidizing agents for use in the CVD process may be any gaseous reactantwhich is capable of reacting with the Ru precursor compounds at thedecomposition temperatures of the latter to formRu—RuSi_(x)—RuSi_(x)O_(y) films. Suitable oxidizing agents for use withthe present method include, but are not limited to, air, oxygen, andoxygen-containing compounds, such as nitrous oxide, tetrahydrofuran, andcarbon dioxide, and are preferably selected from mildly oxidizinggaseous oxygen sources.

CVD may be defined as the formation of a nonvolatile, solid film on asubstrate by the reaction of vapor phase reactants, i.e., reactantgases, that contain desired components. The reactant gases areintroduced into the reaction chamber. The gases decompose and react at aheated wafer or other semiconductor substrate surface to form thedesired layer. Chemical vapor deposition is just one process ofproviding thin layers on semiconductor wafers, such as films ofelemental metals or compounds (e.g., platinum, ruthenium oxide, iridium,molybdenum oxide, etc). Chemical vapor deposition processes are favoredin many respects because of the process capability to provide highlyconformal layers even within deep contacts and other openings. Thus, asdescribed further below with reference to FIGS. 5 and 6, CVD processingis preferably used to provide highly conformal layers within deepcontacts and other openings such as for lower electrodes of storage cellcapacitors. It will be readily apparent to one skilled in the art thatalthough CVD is the preferred process, that the CVD process may beenhanced by various related techniques such as plasma assistance, photoassistance, laser assistance, as well as other techniques. In addition,atomic layer deposition could be used to form conformal layers. This isa variant of CVD in which a single atomic layer is formed on thesurface. The layer thickness is self limiting to ≦1 atomic layer. Thislayer is exposed to reaction gas after pump down or purge, is fullyreacted, and the reaction gas pumped away. The process is repeated toyield the desired number of layers.

In addition, atomic layer deposition could be used to form the layer.This process is a special type of CVD in which, based on the processconditions and/or chemistry used, at most, a single layer comprising asingle type of organometallic precursor is deposited at one time.Accordingly, the thickness of the layer is, at most, the thickness ofthe relevant adsorbed species, at which point no more precursor willadsorb; hence, the layer may be referred to as a “monolayer.” Once onemonolayer is deposited, the deposition gas is purged and a secondreaction gas is introduced to react with the first monolayer to producethe desired compound and activate the surface for the next step.Additional monolayers may be provided in a similar manner, provided thegases from earlier deposition steps are purged from the chamber beforeeach subsequent monolayer is deposited.

One preferred method of forming the RuSi_(x)O_(y)-containing adhesionlayer 23 is by depositing RuSi_(x) by CVD. The CVD process is conductedwith a ruthenium precursor being delivered to a reaction chamber alongwith a silicon precursor. Typical ruthenium precursors in use includeliquid ruthenium metal-organic precursors. The ruthenium precursor iscontained in a bubbler reservoir through which a carrier gas, such ashelium or any other inert gas, i.e., a gas that is nonreactive withother gases of the process (e.g., nitrogen, argon, neon, and xenon), isbubbled through the reservoir containing the precursor to deliver theprecursor to the reaction chamber. For example, a carrier gas having avolumetric flow rate in the range of about one sccm to about 500 sccmmay be used in a bubbler having a pressure in the range of about 0.5torr to about 50 torr and a temperature in the range of about 30° C. toabout 70° C. to deliver a ruthenium precursor to the reaction chamber.

Any ruthenium containing precursor may be used in accordance with thepresent invention. Preferably, the ruthenium precursors are liquidruthenium complexes of the following formula (Formula I): (diene)Ru(CO)₃wherein: “diene” refers to linear, branched, or cyclic dienes, bicyclicdienes, tricyclic dienes, fluorinated derivatives thereof, combinationsthereof, and derivatives thereof additionally containing heteroatomssuch as halide, Si, S, Se, P, As, or N. These precursor complexes andothers, as well as various CVD processes, are described in Assignees'copending patent application U.S. Ser. No. 09/141,236, entitled“Precursor Chemistries for Chemical Vapor Deposition of Ruthenium andRuthenium Oxide,” and in Assignees' copending patent applicationentitled “Methods for Preparing Ruthenium and Osmium Compounds” havingU.S. Ser. No. 09/141,431, both of which are incorporated by referenceherein. Additional precursors and methods of depositing ruthenium layersare generally discussed in U.S. Pat. No. 5,372,849 to McCormick et al.,which is incorporated by reference herein. More preferably, theruthenium precursors used according to the present invention include oneof C₆H₈Ru(CO)₃,(C₇H₁₀)Ru(CO)₃, bis(cyclopentadienyl) ruthenium (II),triruthenium dodecacarbonyl, and cyclopentadienyl dicarbonyl ruthenium(II) dimer.

The silicon precursor is also provided to the reaction chamber. Forexample, the silicon precursor may include a silicon hydride or silanesuch as dichlorosilane (DCS, SiH₂Cl₂), silane (SiH₄), disilane(H₃SiSiH₃), trichlorosilane (TCS, SiHCl₃), or any other siliconprecursor as would be recognized by one skilled in the art. For example,the silicon precursor may be provided to the reaction chamber at a ratein the range of about 0.1 sccm to about 500 sccm. Preferably, the rateis about 10 sccm.

One skilled in the art will recognize that the manner in which the gasesare introduced into the reaction chamber may include one of varioustechniques. For example, in addition to provision by bubbler techniques,the introduction may be accomplished with the use of compounds which aregases at room temperature or by heating a volatile compound anddelivering the volatile compound to the reaction chamber using a carriergas. Further, solid precursors and various methods of vaporizing suchsolid precursors may also be used for introduction of reactant compoundsinto the chamber. As such, the present invention is not limited to anyparticular technique. For example, reactant gases can be admitted atseparate inlet ports. In addition to the other gases provided to thereaction chamber, an optional carrier or dilution gas (i.e., a gas thatis nonreactive with the reactant gases) may also be introduced into thechamber such as to change the concentrations of the gases therein. Forexample, argon gas may be introduced into the chamber at a varied flowrate. Oxidizing gases can also be introduced into the reaction chamberwhen an oxidizing atmosphere is desired.

In accordance with one method of forming the RuSi_(x)O_(y)-containingadhesion layer, the ruthenium precursor gas, the silicon precursor gas,optionally a dilution gas, and an oxidizing gas (if necessary) isprovided to the reaction chamber. In this preferred CVD process, thereaction chamber pressure is preferably maintained at a depositionpressure of about 0.1 torr to about 10 torr. The deposition temperatureat the wafer surface upon which the RuSi_(x)O_(y) adhesion layer 23 isdeposited is preferably held at a temperature in a range of about 100°C. to about 700° C., more preferably in the range of about 200° C. toabout 500° C.

Another preferred method of forming a RuSi_(x)O_(y)-containing adhesionlayer 29 according to the present invention is shown in FIGS. 2-4. Thismethod forms the RuSi_(x)O_(y)-containing adhesion layer 29 bydepositing a layer of ruthenium 28, as shown in FIG. 2, onto asilicon-containing region of substrate assembly 26 using a CVDtechnique. Generally, the method can be carried out by introducing aruthenium precursor composition into a CVD chamber together with acarrier or dilution gas, as described in Applicant's Assignees'copending patent application entitled “Methods for Preparing RutheniumOxide Films,” having Ser. No. 09/140,932, the disclosure of which isincorporated by reference herein. This ruthenium deposition step isfollowed by an annealing process to react the silicon-containing regionhaving silicon-containing surface 27 with the ruthenium layer 28. Theannealing process is carried out in an oxidizing atmosphere, such asoxygen gas, to further oxidize the deposited layer and to form theRuSi_(x)O_(y)-containing adhesion layer 29 shown in FIG. 3. Variouscombinations of carrier gases and/or reaction (oxidizing) gases can beused in the methods of the present invention. The gases can beintroduced into the CVD deposition chamber in a variety of manners, suchas directly into a vaporization chamber of the CVD deposition chamber orin combination with the ruthenium precursor composition. Thereafter, aconductive layer 31 (e.g., the conductive layer 24 of FIG. 1) is formedon the RuSi_(x)O_(y)-containing adhesion layer 29, as shown in FIG. 4.

The annealing process is preferably performed in situ in the reactionchamber in a nitrogen atmosphere, although any other nonreactiveatmosphere may be used, e.g., argon. Preferably, the annealingtemperature is within the range of about 400° C. to about 1000° C., morepreferably about 500° C. The anneal is preferably performed for a timeperiod of about 0.5 minutes to about 60 minutes. One of ordinary skillin the art will recognize that such temperatures and time periods mayvary and that the anneal parameters should be sufficient to convert theruthenium layer 28, following oxidation, into RuSi_(x)O_(y) 29, where xand y are in the ranges previously described herein. For example,various anneal techniques (e.g., furnace anneals, anneal, process RTP,and rapid thermal smearing) may be used and may be performed in one ormore annealing steps. Likewise, it may not be necessary or desirable toconvert the entire ruthenium layer to RuSi_(x)O_(y) as long assufficient adhesion properties are attained with the amount of rutheniumconverted.

The ruthenium layer 28 deposited for forming theRuSi_(x)O_(y)-containing adhesion layer 29 is preferably of a thicknessin the range of about 10 Å to about 1000 Å. More preferably, thethickness is in the range is about 50 Å to about of 500 Å, and even morepreferably, the thickness is about 300 Å.

Referring to FIG. 5, a structure 30 is shown which includes a substrateassembly 32 (e.g., a silicon substrate region) and a stack 34. The stack34 includes conductive layers 41-44. One or more of the conductivelayers 41—44 may be RuSi_(x)O_(y)-containing adhesion layers accordingto the present invention. The one or more conductive layers, in additionto including one or more RuSi_(x)O_(y)-containing adhesion layers, mayinclude conductive layers formed of various conductive materials. Forexample, the conductive layers may include, but are not limited to,layers formed of metals, metal oxides or combinations thereof. By way ofexample, the conductive layers may include metals such as rhodium,palladium, ruthenium, platinum, and iridium or metal oxides such asruthenium oxide, rhodium oxide, molybdenum oxide and iridium oxide.

The stack 34 may be used for various applications, such asinterconnection applications and capacitor applications. For example,the stack 34 may be used as an electrode for a storage cell capacitorwith the substrate assembly 32 including a silicon-containing surface33. In accordance with the present invention, the layer 41 may be formedas the RuSi_(x)O_(y)-containing adhesion layer to adhere or enhanceadhesion (prevent delamination) between layer 42 and substrate assembly32 and to also prevent oxygen diffusion to the silicon-containingsurface 33 of substrate assembly 32.

FIG. 6 shows a structure 50 including substrate assembly 52 (e.g., asilicon substrate) and capacitor structure 54 formed relative thereto.Capacitor structure 54 includes a first electrode 56, a second electrode60, and a high dielectric constant layer 58 interposed therebetween. Thedielectric layer may be of any suitable material having a desirabledielectric constant, such as, for example, Ba_(x)Sr_((1−x))TiO₃ [BST],BaTiO₃, SrTiO₃, PbTiO₃, Pb(Zr,Ti)O₃ [PZT], (Pb,La)(Zr,Ti)O₃ [PLZT],(Pb,La)TiO₃ [PLT], Ta₂O₅, KNO₃, and/or LiNbO₃. With use of the highdielectric constant layer 58, adhesion properties between theaforementioned layers and resistance to oxidation in the underlyingsubstrate assembly 52 and/or portions of the capacitor structure 54 areparticularly important.

In a bottom electrode of a capacitor structure, such as that shown inFIG. 6, the electrode layer or electrode stack must be sufficientlyadhered to prevent delamination during various process steps (e.g.,anneal process), particularly due to the high temperature processes usedto form the high dielectric constant materials, and to also act as aneffective oxidation barrier to the underlying silicon substrate. Suchproperties are particularly essential when the substrate assembly 52includes a silicon-containing surface 53 (e.g., polysilicon, siliconsubstrate material, N-doped silicon, P-doped silicon) upon which thecapacitor is formed, due to oxidation of the diffused silicon which mayresult in degraded capacitance, such as that seen in memory devices.Additionally, the electrode stack must act as an oxygen barrier toprotect the silicon-containing surface under the stack from oxidizing.The formation of the RuSi_(x)O_(y)-containing adhesion layer enhancesthe oxidation-resistance properties of the stack. One of ordinary skillin the art will recognize that the first electrode 56 includes one ormore RuSi_(x)O_(y)-containing adhesion layers and one or more additionalconductive layers, as described with reference to FIG. 5.

The RuSi_(x)O_(y)-containing adhesion layers of the present inventionhave numerous and varied applications in the area of semiconductordevice and semiconductor structure fabrication. For example, the use ofRuSi_(x)O_(y)-containing adhesion layers of the present invention isdescribed with reference to FIG. 7, wherein a contact liner requiringadhesion and oxidation barrier characteristics is described. Morespecifically, device structure 70 is fabricated in accordance withconventional processing techniques through the formation of contactopening 102 prior to metallization of the contact area 94 of substrate80. As such, prior to metallization, the device structure 70 includesfield oxide regions 82 and active areas (represented by regions ofsubstrate 80 not covered by field oxide). Word line 92 and field effecttransistors (FET) 90 are formed relative to the field oxide regions 82in the active areas. Suitably doped source/drain regions 84, 86 areformed by conventional methods known to one of ordinary skill in theart. A conformal layer of oxide material 88 is formed thereover andcontact opening 102 is defined therein to the contact area 94 of dopedsource region 84 of substrate 80. Thereafter, one or more metallizationor conductive layers (e.g., titanium nitride) are formed in the contactopening 102 for providing electrical connection to doped source/drainregions 84. Preferably, contact liner 100 is a RuSi_(x)O_(y)-containingadhesion layer formed according to the present invention on bottomsurface 96 and the one or more side walls 98 defining the contactopening 102. The RuSi_(x)O_(y)-containing adhesion layer is generallydeposited over the entire substrate assembly and then planarized to formthe contact liner 100. Thereafter, a conductive material 104 ( e.g.,aluminum, W, Cu) is formed in the contact opening for providingconnection to doped source/drain regions 84 of substrate 80.

Alternatively, the present invention may be used to fabricate a bottomelectrode of a high dielectric capacitor of a storage cell that includesone or more RuSi_(x)O_(y)-containing adhesion layers, as shown in FIG.8. Specifically, a device structure 106 is fabricated in accordance withconventional processing techniques through the formation of an opening114 prior to depositing a bottom electrode structure 118 on the surface112 (preferably a silicon-containing surface) and surface 116 definingthe opening 114. A bottom electrode structure 118, which includes aRuSi_(x)O_(y)-containing adhesion layer and one or more other conductivelayers is formed in opening 114 according to the present invention, aspreviously described herein. The substrate assembly 110 may includevarious elements, such as field oxide regions, active regions (i.e.,regions of a silicon substrate not covered by field oxide), word lines,field effect transistors (FET), and source/drain regions created in thesilicon substrate. An insulative layer of oxide material 113 is formedover the substrate assembly 110. The opening 114 in the insulative layerof oxide material 113 is a small, high aspect ratio opening. Asdescribed herein, small, high aspect ratio openings have feature sizesor critical dimensions below about 1 micron (e.g., such as a diameter orwidth of an opening being less than about 1 micron) and aspect ratios(ratio of depth to width) greater than about 4. Such aspect ratios areapplicable to contact holes, vias, trenches, and any other configuredopenings. For example, a trench having an opening of 1 micron and depthof 3 microns has an aspect ratio of 3. The present invention isparticularly useful in the formation of adhesion layers in small, highaspect ratio features due to the use of CVD processes for formingconformal RuSi_(x)O_(y)-containing adhesion layers over step structures.

As shown in FIG. 8, a bottom electrode structure 118, including aRuSi_(x)O_(y)-containing adhesion layer, is formed on the surface 112and the one or more surfaces 116 defining opening 114. In thisparticular embodiment of the invention, the electrode stack layers areformed over the entire structure, including the surface 112 and surfaces116. The layers are then formed into bottom electrode structure 118. Byway of example, the stack layers may be etched or planarized to removedesired regions for forming the bottom electrode structure 118.Thereafter, dielectric layer 120 is formed relative to the bottomelectrode structure 118. The second electrode 192 is then formedrelative to the dielectric material 120. Such an electrode may, forexample, be composed of any suitable conductive material, such astungsten nitride, titanium nitride, tantalum nitride, ruthenium,rhodium, iridium, ruthenium oxide, iridium oxide, any combinationthereof, or any other conductive material typically used as an electrodeor electrode layer of a storage cell capacitor. In accordance with theinstant embodiment of the present invention, the bottom electrode isconformally formed of a stack of layers, including aRuSi_(x)O_(y)-containing adhesion layer, having uniform thickness anddeposited using CVD processes to provide suitable oxidation-resistantadhesive properties.

It will be recognized by one skilled in the art that, in addition to theembodiments described herein, any capacitor formed relative to a surface(e.g., silicon-containing surface) whereupon adhesion and oxidationbarrier properties are required, and/or conformally formed, conductivelayers are required, may benefit from the present invention. Forexample, container capacitors typically include electrodes formed onsurfaces requiring conformal formation of a bottom electrode. Such acontainer capacitor storage cell is described in U.S. Pat. No. 5,270,241to Dennison, et al., entitled “Optimized Container Stack Capacitor DRAMCell Utilizing Sacrificial Oxide Deposition and Chemical MechanicalPolishing,” issued Dec. 14, 1993, and incorporated herein by thisreference. The present invention may also be employed in the fabricationof other semiconductor processes and structures for various devices(e.g., CMOS devices, memory devices, logic devices, etc.). It should beunderstood that the present invention is not limited to the illustrativeembodiments described herein and that the RuSi_(x)O_(y)-containingadhesion layer of the present invention may be used for any applicationrequiring adhesion and oxidation barrier characteristics, particularlythose for preventing diffusion of silicon and/or oxygen into adjacentlayers.

A RuSi_(x)O_(y) adhesion layer was formed by a conventional CVD process.The reaction chamber used for fabricating the sample wafer was a CVDchamber manufactured by Plasma Quest (Dallas, Tex.) and the bubblersused are glass research bubblers from Technical Glass Service (Boise,Ind.). The conditions used for forming the RuSi_(x)O_(y)-containingadhesion layer include:

Ruthenium Precursor: C₆H₈Ru(CO)₃.

Ruthenium Carrier Gas for use through Bubbler: 50 sccm of helium.

Ruthenium Bubbler Conditions: pressure of 3 torr, temperature of 25° C.

Reaction Chamber Conditions: pressure of 0.5 torr, depositiontemperature of 305° C. at wafer surface, 5 sccm SiH₄.

Deposition Time: 0.5 minute.

The conditions used for the forming the ruthenium oxide layer include:

Ruthenium Precursor: C₆H₈Ru(CO)₃.

Ruthenium Carrier Gas for use through Bubbler: 50 sccm of helium.

Ruthenium Bubbler Conditions: pressure of 3 torr, temperature of 25° C.

Reaction Chamber Conditions: pressure of 3 torr, deposition temperatureof 230° C. at wafer surface.

Deposition Time: 3 minutes.

It will be recognized by a person having skill in the art that, inaddition to the embodiments described herein, the present invention maybe carried out to include controlled deposition of one or more“monolayers” of RuSi_(x)O_(y)-containing adhesion layer(s). Thisprocess, typically referred to as atomic layer deposition, atomic layerepitaxy, sequential layer deposition, or pulsed-gas CVD, involves use ofa precursor based on self-limiting surface reactions. Generally, asubstrate is exposed to a first species that deposits as a monolayer andthe monolayer then being exposed to a second species to form a fullyreacted layer plus gaseous byproducts. The process is typically repeateduntil a desired thickness is achieved. Atomic layer deposition andvarious methods to carry out the same are described in U.S. Pat. No.4,058,430 to Suntola et al., entitled “Method for Producing CompoundThin Films,” U.S. Pat. No. 4,413,022 to Suntola et al., entitled “Methodfor Performing Growth of Compound Thin Films,” Ylilammi, “MonolayerThickness in Atomic Layer Deposition,” Thin Solid Films 279 (1996)124-130, and S. M. George et al., “Surface Chemistry for Atomic LayerGrowth,” J. Phys. Chem. 1996, 100, 13121-13131, the disclosures of eachsuch document are hereby incorporated by reference.

The process has also been described as a CVD operation performed undercontrolled conditions which cause the deposition to be self-limiting toyield deposition of, at most, a monolayer. The deposition of a monolayeris significant in many areas because it facilitates theoreticallyconformal films, precise control of film thickness, and improvedcompound material layer uniformity. In practice, however, the deposited“monolayer” is rarely a complete and true monolayer, there always beingsomething less than complete coverage of an underlying layer or othersurface due to the space consumed by the non-incorporating components ofthe metal organic precursor. Combinations of deposition processesdiscussed herein may be used to provide deposition materials (e.g.,Atomic Layer Deposition (ALD) and non-ALD types of CVD). Accordingly,exemplary embodiments of the invention include within their scopedeposition of a monolayer under conditions designed to achieve suchresults, as well as conditions with a subsequent shift of conditionstoward the CVD regime, such that, to the extent required, the depositionof the RuSi_(x)O_(y)-containing adhesion layers is effected as 3-5“monolayers” rather than a single monolayer.

More specifically, deposition of monolayers is accomplished in a CVDchamber, as previously described with reference to the CVD depositionmethod, but with the addition of pulsing valves to allow the switchingbetween the precursor and purge gas and the SiH₄ (Si₂H₆) and purge gas.Bubblers, however, are not required since carrier gases may or may notbe used, depending on the configuration of the vacuum system. For thisexample, a simple storage ampule with a single outlet and no inlet isused. As with the CVD method, C₆H₈Ru(CO)₃ is used as the rutheniumprecursor. The deposition temperature of the wafer surface is 50-250degrees C. and the reaction chamber is kept at a variable pressure rangeof about 0.5 torr to about 0.0001 torr. The reaction chamber is fullyopened to the pumps of the vacuum system to create a vacuum in the CVDchamber and the ruthenium precursor gas is introduced at low pressure,preferably about 0.0001 torr. Introduction of the ruthenium precursorgas under these conditions will result in the deposition of, at most, amonolayer of ruthenium over the surface of the wafer. A purge cycle isthen initiated by introducing a nonreactive gas, such as He or Ar, at avolumetric flow rate of about 50 sccm into the reaction chamber at 0.5torr. It is understood that any suitable nonreactive gas may be used andthat the nonreactive gas may be introduced at a rate of between about0.1 sccm to about 500 sccm to optimize system conditions. Silane ordisilane is introduced into the reaction chamber at a rate of about 5sccm, which results in the deposition of a silicon monolayer over thepreviously deposited ruthenium monolayer. This is followed by a purgecycle of nonreactive gas, as previously described. It is understood thatoxygen can be added as a separate oxygen/purge cycle as needed for everyindividual cycle in order to give the required oxygen content. Ingeneral, however, sufficient oxygen is available from background O₂ andH₂O in the chamber to oxidize the underlying RuSi_(x) layer formed inthe preceding steps. The monolayer of adsorbed precursor from theinitial precursor deposition step will react directly when exposed tothe reaction gas in the third step of the foregoing doseprecursor/purge/dose reaction gas/purge sequence, which results incontrolled deposition of one or more RuSi_(x)O_(y)-containing adhesionmonolayers.

Although this invention has been described with reference toillustrative embodiments, it is not meant to be construed in a limitingsense. As described previously, one skilled in the art will recognizethat various other illustrative applications may use theRuSi_(x)O_(y)-containing adhesion layer as described herein to takeadvantage of the beneficial adhesion and oxidation resistancecharacteristics thereof Various modifications of the illustrativeembodiments, as well as additional embodiments to the invention, will beapparent to persons skilled in the art upon reference to thisdescription. It is therefore contemplated that any such modifications orembodiments may fall within the scope of the present invention asdefined by the accompanying claims.

What is claimed is:
 1. A method for forming a semiconductor devicestructure comprising: providing a semiconductor substrate assemblyhaving a surface; and forming an adhesion layer over at least a portionof the surface, wherein the adhesion layer comprises RuSi_(x)O_(y). 2.The method of claim 1, wherein forming the adhesion layer over at leasta portion of the surface comprises forming a layer of RuSi_(x)O_(y)where x is in a range of about 0.01 to about
 10. 3. The method of claim2, wherein forming the adhesive layer over at least a portion of thesurface comprises forming a layer of RuSi_(x)O_(y) where x is about 0.4.4. The method of claim 1, wherein forming the adhesion layer over atleast a portion of the surface comprises forming a layer ofRuSi_(x)O_(y) where y is in a range of about 0.01 to about
 10. 5. Themethod of claim 4, wherein forming the adhesive layer over at least aportion of the surface comprises forming a layer of RuSi_(x)O_(y) wherey is about 0.05.
 6. The method of claim 1, wherein forming the adhesionlayer includes depositing RuSi_(x)O_(y) by chemical vapor deposition. 7.The method of claim 1, wherein forming the adhesion layer includesdepositing RuSi_(x)O_(y) by atomic layer deposition.
 8. The method ofclaim 7, wherein forming the adhesion layer includes depositing three tofive monolayers of RuSi_(x)O_(y).
 9. The method of claim 1, whereinforming the adhesion layer includes depositing RuSi_(x)O_(y) by physicalvapor deposition.
 10. The method of claim 1, wherein forming theadhesion layer comprises: forming a layer of ruthenium relative to asilicon-containing region; and performing an anneal in an oxidizingatmosphere to form RuSi_(x)O_(y) from the layer of ruthenium and thesilicon-containing region.
 11. The method of claim 10, wherein formingthe layer of ruthenium includes depositing the layer of ruthenium bychemical vapor deposition.
 12. The method of claim 10, wherein formingthe layer of ruthenium includes depositing the layer of ruthenium byatomic layer deposition.
 13. The method of claim 10, wherein forming thelayer of ruthenium includes depositing three to five monolayers ofRuSi_(x)O_(y).
 14. The method of claim 10, wherein performing the annealin the oxidizing atmosphere includes performing an anneal in anatmosphere including an oxidizing gas.
 15. The method of claim 1,further including forming at least one additional conductive materialover the adhesion layer, and selecting the at least one additionalconductive material from a group of a metal and a conductive metaloxide.
 16. The method of claim 10, wherein performing the anneal to formsaid RuSi_(x)O_(y) includes performing an anneal at a temperature in arange of about 400° C. to about 1000° C.
 17. The method of claim 10,wherein performing the anneal in an oxidizing atmosphere to formRuSi_(x)O_(y) from the layer of ruthenium and the silicon-containingregion comprises performing the anneal in an atmosphere comprising air,oxygen, and oxygen-containing compounds.
 18. The method of claim 10,further including providing said silicon-containing region as at least aportion of a semiconductor substrate.
 19. The method of claim 1, whereinforming the adhesion layer comprises forming an adhesion layer in anoxidizing atmosphere.
 20. The method of claim 19, wherein forming theadhesion layer in an oxidizing atmosphere comprises forming an adhesionlayer in an atmosphere including an oxidizing gas.